pH值对碱溶法罗非鱼鱼糜制备及凝胶性质的影响

在pH0.5~12.5的范围内,采用碱溶法制备了罗非鱼鱼糜(TS)。研究表明,随着pH值的升高,TS蛋白回收率得到显著提高,但在pH值由11.5升至12.5时,得率仅提高11.56%,而碱液耗费却增加了77.65%;pH值的升高使溶解蛋白的ATP酶活性急剧降低(51.80%→0%),而表观疏水性则表现出增强趋势,表明pH值的升高促进了肌球蛋白的构象展开。电泳结果显示,pH值升高并未使等电点处可溶性蛋白及TS中蛋白组分发生明显变化。pH值的升高使TS白度先升高(75.40→80.50),之后下降(→76.20);TS凝胶破断力也表现出先升高后下降的趋势(290.00→335.20→278.80g),表明极端的碱性条件(pH12.0)会对TS凝胶品质产生负面影响。TS凝胶的电泳结果表明,不同pH值条件下提取的TS所制备的凝胶蛋白组分之间没有明显差别,并且TS凝胶形成过程中没有显著的肌球蛋白交链发生,意味着TS中内源谷氨酰胺转胺酶(TG酶)活性相对于传统鱼糜变得很低,这可能是由于在等电点处离心时TG酶与TS发生了分离。     

超高压诱导鱼糜凝胶性能的研究

本文研究了压力对六齿金线鱼鱼糜凝胶的凝胶特性、溶解度、电泳和TCA-可溶性肽含量的影响,并与热处理的结果对比。研究表明,压力诱导凝胶的凝胶强度随压力增大而增大,600MPa处理的凝胶强度达到最大值为429．775g-cm,比热处理凝胶高23．03％。与热处理样相比,压力诱导凝胶的硬度、咀嚼性较低,内聚性较高,弹性在200MPa以上时较高,持水性较好,白度较低。压力诱导凝胶的溶解度高于热处理凝胶,SDS-PAGE显示其肌球蛋白重链较深,表明压力会使内源性转谷氨酰胺酶的活性降低,不利于形成ε-（γ一谷氨酰）赖氨酸键。压力诱导凝胶的TCA-可溶性肽含量低于热处理凝胶,表明压力可抑制引起鱼糜凝胶劣化的内源性水解蛋白酶的活性。结果表明,超高压处理有利于形成柔软、有弹性和凝胶强度高的凝胶;对内源性水解蛋白酶活性的抑制作用可能是超高压改善其凝胺特性的主要原因之一。     

Color and Quality of Mackerel Surimi as Affected by Alkaline Washing and Ozonation

Washing with alkaline phosphate or bicarbonate buffers (>pH 8.0) did not remove the pigments from minced mackerel. Thirty min ozonation in citrate buffer (pH 3.0) increased the whiteness (51.7 to 60.1) and L value (53.9 to 62.6), and decreased myoglobin (47.8 to 12.2 mg/100g) and total pigments (78.5 to 15.5 mg/100g). However, the deformation of surimi decreased from 0.90 cm to 0.45 cm, even though there was no change in breaking force. In comparison with untreated sample, addition of 0.10% NaHSO₃, 0.15% cysteine or 0.20% ascorbic acid during grinding resulted in substantial recovery of the deformation and breaking force of ozonated surimi.     

鸡蛋清蛋白对微生物转谷氨酰胺酶诱导鲢鱼鱼糜凝胶形成的影响

通过对鲢鱼鱼糜凝胶特性和溶解率的测定及SDS-PAGE检测研究鸡蛋清蛋白改善鱼糜凝胶特性的机理及其对微生物转谷氨酰胺酶(MTGase)诱导鱼糜凝胶形成的影响。结果表明：鸡蛋清蛋白(EA)和MTGase均能显著提高鱼糜凝胶特性。EA会降低MTGase诱导鱼糜凝胶的形成,显著降低MTGase诱导鱼糜凝胶的凝胶强度和破断强度,但不阻碍MTGase对肌球蛋白重链(MHC)的交联。     

谷氨酰胺转氨酶对竹荚鱼鱼糜蛋白凝胶特性的影响

以质构、白度和持水力为指标研究谷氨酰胺转氨酶(TGase)添加量、凝胶化时间和凝胶化温度对竹荚鱼鱼糜凝胶特性的影响。结果表明：当TGase 添加量为80U/100g 鱼糜、凝胶化时间为5h、凝胶化温度为37.5℃时,竹荚鱼鱼糜的凝胶特性达到最佳,能够形成高度致密、均匀的凝胶网络结构。采用二段加热法制备的竹荚鱼鱼糜凝胶的特性好于一段加热法。     

转谷氨酰胺酶对鳙鱼鱼糜凝胶特性的影响

研究了不同浓度的转谷氨酰胺酶 (简称TGase)对鳙鱼鱼糜凝胶特性的影响。结果表明 ,在鳙鱼鱼糜中添加不同浓度的TGase ,均可使其凝胶的破断强度、凹陷深度、凝胶强度及持水性增加 ,而对其颜色、白度无影响 ;酶的最佳浓度为 0 5 % ,在此浓度下 ,鱼糜的凝胶强度为 2 13 0 9g·cm ,是对照样的 4倍多 ;通过对SDS 聚丙烯酰胺凝胶电泳及溶解度的分析表明 ,TGase可催化鳙鱼鱼糜中的肌球蛋白重链 (MHC)形成共价交联键。电镜分析则表明 ,TGase的加入可使鳙鱼鱼糜形成致密、均匀的凝胶网络结构     

Heat Gelation Properties of Actomyosin and Surimi Prepared from Atlantic Croaker

Comminuted mixtures of fish muscle (surimi) and salt undergo a sol-gel transformation when subjected to heat processing which is responsible for the textural characteristics of fabricated imitation shellfish meats. Upon “setting” a fish muscle sol at temperatures below those conventionally used for heat processing meat products, a fine translucent gel network is formed which imparts strength and resiliency to the subsequently cooked gel product. Increased firmness and opacity, as well as some loss in cohesiveness, were noted upon processing surimi sols at higher temperatures. The low temperature “setting” property of fish proteins necessitates rapid forming or extrusion of the product prior to the initiation of network formation to insure a firm texture in the final product.     

两种微波加热处理方式对白鲢鱼糜凝胶特性的影响

为提高鱼糜制品的品质,研究两种微波加热处理(单独微波和水浴微波联用)对白鲢鱼糜凝胶特性的影响。以凝胶强度、持水性、白度为检测指标,采用单因素和正交试验,优化得到单独微波加热和水浴微波联用加热的工艺条件;并采用凝胶溶解度、化学作用力、SDS-PAGE凝胶电泳、扫描电镜等检测方法,进一步研究不同加热处理方式对鱼糜凝胶蛋白质分子结构的影响。优化试验结果表明,单独微波加热的最佳工艺条件为微波功率600 W、微波时间60 s,此时凝胶强度608.64 g·cm,持水性83.64%,白度75.79;水浴微波联用加热的最佳工艺条件为水浴温度40℃,水浴时间1 h,微波功率450 W、微波时间60 s,此时凝胶强度627.37 g·cm,持水性85.37%,白度74.37。验证试验结果表明,在提高白鲢鱼糜凝胶特性方面,两种微波加热显著优于传统水浴加热(即水浴二段加热),且水浴微波联用加热比单独微波加热更好。     

苹果多酚改性蛋清改善鲅鱼鱼糜的凝胶性质

为探讨苹果多酚改性蛋清对鲅鱼鱼糜性质的作用机制,将质量比分别为0.50%、0.75%、1.00%、1.25%、1.50%苹果多酚改性的蛋清加入鱼糜中,与控制组（只添加蛋清）及空白组对比,通过测定凝胶特性;测定鱼糜凝胶的TVB-N、菌落总数、TBARS、以及TPA参数随贮藏时间的变化;检测鲅鱼鱼糜肌原纤维蛋白的圆二色谱、及紫外吸收光谱。结果显示添加苹果多酚改性蛋清的鱼糜凝胶强度（2962.81、3342.79、3088.05、2527.83、2147.12 mm?g）、持水性（0.87%、0.85%、0.87%、0.86%、0.86%）有着显著性的提升（p<0.05）,随着苹果多酚浓度的增加,鱼糜的L*（亮度）从69.58降至64.10,a*（红绿值）从-1.83升至1.23（p<0.05）;鱼糜凝胶硬度、弹性、回复性存在先上升后下降的趋势;在贮藏期内,挥发性盐基氮值、过氧化值和菌落总数值相对于空白组均有显著性下降（p<0.05）。经过苹果多酚改性蛋清处理的鱼糜肌原纤维蛋白,0.5% AP-EW组相对于空白组的α-螺旋含量增加了1.87%,β-转角和无规卷曲相对含量有降低。结果证明苹果多酚改性蛋清的添加可显著提高鲅鱼鱼糜的凝胶性质。     

Gel Strength Enhancement by Addition of Microbial Transglutaminase during Onshore Surimi Manufacture

Surimi from Alaska pollock flesh was manufactured onshore with Microbial transglutaminase (MTGase). Effect of MTGase was investigated by evaluating breaking strength and deformation of gels from MTGase-treated surimi with and without setting at 30°C. Quantitative analysis of ε-(γ-glutamyl)lysine (GL) crosslink was also carried out to monitor the MTGase reaction. In set gels, breaking strength and GL crosslink increased, and myosin heavy chain decreased correspondingly with MTGase concentration. These changes were smaller in gels prepared without setting. Results suggest that surimi gel could be improved through the formation of GL crosslinks by added MTGase in surimi.     

Protein Extraction from Beef Heart using Acid Solubilization

ABSTRACT: The recovery of myofibrillar protein from beef heart using nonthermal acidic solubilization was evaluated. Postmortem time, 3 or 24 h, did not affect protein solubility ( p > 0.05). Protein solubility and yield were detrimentally affected by salt addition. Recovery of extracted protein (yield) was maximized with 0 mM NaCl (60.8 ± 3.9%). SDS-PAGE confirmed myosin solubilization below pH 5 and suggested reduced protein solubility below pH 2.5. Extracted protein from beef heart was significantly lower in fat, cholesterol, ash, and total collagen. In addition, the protein profile using a 7% SDS-Page gel consisted mainly of heavy chain myosin (36%), 150 kDa proteins (15%), and actin (21%).     

Effect of pH-Shift Processing and Surimi Processing on Atlantic Croaker (Micropogonias undulates) Muscle Proteins

ABSTRACT:  Extraction and recovery of fish muscle proteins with the pH-shift process was investigated for Atlantic croaker and compared to a laboratory scale surimi process. The acid-aided process led to higher recoveries ( P < 0.05) than the alkali-aided process, which in turn led to higher recoveries ( P < 0.05) than surimi processing. Lipid reductions were highest ( P < 0.05) for the alkali-aided process, followed by the acid-aided process, with surimi giving the least reduction. No major differences in recovered proteins could be seen for the three processes, except both pH-shift processes had a protein band (∼150 KDa) possibly representing partial hydrolysis of myosin. Oscillatory rheology on protein pastes during heating and cooling showed the highest storage moduli for the alkali-aided isolate, followed by the acid aided isolates and surimi. Torsion testing on protein gels demonstrated significantly higher strain and stress values for gels made from frozen isolates with added cryoprotectants compared to fresh gels without added cryoprotectants. Gel stress was significantly higher ( P < 0.05) for the frozen gels with added cryoprotectants made from the isolates, compared to surimi. Although isolate pastes had higher ( P < 0.05) lightness values than surimi pastes, surimi gels had higher ( P < 0.05) lightness than isolate gels. The acid-aided gels had higher levels of yellowness than the other treatments. Both surimi and alkali-aided isolates had significantly ( P < 0.05) lower oxidation levels compared to the ground raw material. The acid isolate had poor oxidative stability and gave higher oxidation values than the raw material. Surimi and alkali-aided pastes and gels also had higher oxidative stability than acid-aided gels.     

Suppression of Surimi Gel Setting by Transglutaminase Inhibitors

Three types of salted meat paste (3% NaCl, 3% NaCl plus 0.66% NH₄Cl or 3% NaCl plus 0.2% EDTA) were prepared from high and second grade surimi, set at 30°C up to 4 br, and subsequently heated at 85°C for 30 min. The gel strength, crosslinking of myosin heavy chain (MHC) and ?-(γ-glutamyl)lysine (?-(γ-Glu)Lys) content were determined. With extended setting time, gel strength, crosslinking of MHC and the content of a crosslinked product, ?-(γ-Glu)Lys, increased markedly in the gel from the high grade surimi. Such changes were suppressed considerably in the presence of NH₄Cl and EDTA and were not observed in the gel prepared from second grade surimi. These results indicated an active participation of intrinsic transglutaminase in the setting process.     

蓝圆鲹酸/碱等电点沉淀法分离蛋白凝胶特性与消化特性

采用酸/碱等电点沉淀（isoelectric solubilization/precipitation,ISP）法制备蓝圆鲹肌肉分离蛋白（acid/alkaline aided protein isolate,API/KPI）,并对全蛋白（total protein,TP）、肌原纤维蛋白（myofibrillar protein,MP）与分离蛋白的理化特性、凝胶特性以及消化稳定性进行比较研究。结果表明,蓝圆鲹肌肉蛋白在碱性条件下溶解性显著高于酸性条件,经优化后的API与KPI的回收率分别为65.0%与84.6%,显著高于MP（54.0%）。KPI、API与MP的脂肪与灰分含量明显低于TP,其中KPI的粗蛋白含量最高。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳显示KPI与API的蛋白组成与TP相近,但KPI与API的氨基酸组成中甘氨酸与脯氨酸含量显著低于TP。质构与流变学分析结果显示,KPI与API的凝胶强度与储能模量（G’）均明显低于TP与MP,其中TP、MP与KPI的储能模量在50～55 ℃会出现明显的下降趋势,表明发生凝胶劣化现象,而API组无明显变化。扫描电子显微镜结果表明,与90 ℃相比,经55 ℃加热处理的KPI、TP与MP组凝胶结构更加疏松、多孔,这与流变学分析的结果一致。体外模拟胃肠液消化实验表明,MP具有最佳的消化性,API与KPI的消化性相当,且显著高于TP。综上所述,利用ISP制备分离蛋白可显著提高蛋白回收率,且分离蛋白的消化性明显优于TP。由于分离蛋白失去凝胶化能力,故可考虑将其应用于食品蛋白配料领域。     

真空斩拌和钙离子浓度对白鲢鱼糜胶凝特性的影响

本文研究了真空和钙离子对白鲢鱼糜胶凝特性的影响,以期为高品质鱼糜制品的加工提供理论依据。结果如下:随着钙离子浓度增加,常压斩拌的鱼糜凝胶的破断力呈现出先增大后减小、然后增大再减小的趋势,两个峰值对应的浓度分别为20 mmol/kg和40 mmol/kg;蛋白的交联程度逐渐从18.08%增加到30.98%,在钙离子浓度高于30 mmol/kg后逐渐降低并达到最小值14.54%;微观结构从无特征性结构转变为连续的网络结构、再转变为分散的聚集体。真空条件下,鱼糜凝胶特性值(破断力、和蛋白交联度)和微观结构随钙离子浓度变化的趋势与常压条件下相同,但是峰值或转变点所对应的钙离子浓度均低10 mmol/kg。真空和常压条件下,持水性随着钙离子浓度增加均逐渐从80.74%和82.27%分别降低到62.09%和67.23%,白度值逐渐从79.11和79.10分别增加到83.80和83.15。结果表明,真空具有降低钙离子影响鱼糜胶凝特性"效应浓度"的作用。     

碱法制备的4种淀粉-脂肪酸包合物的热力学性质研究

采用差示扫描量热仪、热重分析仪和X-射线衍射仪研究绿豆淀粉、木薯淀粉、甘薯淀粉和马铃薯淀粉对HCl/KOH法制备的淀粉-脂肪酸包合物糊化和热分解性质、玻璃化转变温度(T_g)、结晶结构等的影响。研究表明,淀粉与脂肪酸复合后晶型变为V型。在薯类淀粉-硬脂酸包合物中,马铃薯淀粉-硬脂酸包合物的糊化温度、T_g和热分解稳定性最高,木薯淀粉-硬脂酸包合物的糊化温度、T_g和热分解稳定性最低。在薯类淀粉-油酸包合物中,木薯淀粉-油酸包合物的糊化焓值(?H)最高,热分解稳定性最小;甘薯淀粉-油酸包合物的?H最低,热分解稳定性最大。比较马铃薯淀粉和绿豆淀粉,马铃薯淀粉-硬脂酸包合物的糊化温度、热分解稳定性高于绿豆淀粉-硬脂酸包合物;马铃薯淀粉-油酸包合物的?H和T_g高于绿豆淀粉-油酸包合物。     

钙离子对白鲢鱼糜热诱导凝胶化的影响

本文通过不同浓度钙离子对白鲢鱼糜凝胶的凝胶特性、溶解率及MHC影响的研究,探讨了Ca2+增强白鲢鱼糜凝胶特性的机理及在白鲢鱼糜中的适宜添加量。结果表明,低浓度的钙离子(10、20mmol/kg)可以激活内源性转谷氨酰胺酶,催化MHC之间共价交联形成ε-(γ-Glu)-Lys共价键,导致鱼糜凝胶溶解率降低,MHC减少,凝胶特性增强,且钙离子的最适添加量为20mmol/kg;但是50mmol/kg的钙离子浓度使MHC的交联受阻,致使鱼糜凝胶特性降低,溶解率增加;当钙离子浓度达到80mmol/kg时,钙离子可与鱼糜蛋白之间形成蛋白质-钙-蛋白质的钙桥结构,使凝胶变硬,弹性降低。     

TGase抑制剂对鲢鱼糜热诱导凝胶形成的影响

本实验通过研究三种转谷胺酰胺酶(Tgase)抑制剂对白鲢鱼糜凝胶的凝胶特性、溶解率、催化肌球蛋白重链(MHC)带强度及微观结构的影响,探讨TGase抑制剂对鲢鱼糜热诱导凝胶形成的影响及其抑制效果。结果表明:鲢鱼糜中存在内源TGase;三种TGase抑制剂均抑制鲢鱼糜凝胶的形成,显著提高鱼糜凝胶的溶解率、增强MHC带强度;随抑制剂浓度的增加,鱼糜凝胶特性显著降低,溶解率显著升高,MHC带强度显著增加;酰基转移反应抑制剂氯化铵的抑制效果最好,其次是巯基阻断剂N-甲基顺丁烯亚胺(NEM),EDTA的抑制效果最小。     

High Pressure Effects on Gelation of Surimi and Turkey Breast Muscle Enhanced by Microbial Transglutaminase

High pressure effects on the strength (stress) and elasticity/deformability (strain) of surimi and turkey breast meat gels containing microbial transglutaminase (TGase) were evaluated. Pressurization of muscle proteins at 4°C prior to incubation at 25°C or 40°C (setting) increased gel strength 2–3 fold in uncooked surimi gels, but not in uncooked turkey gels. However, pressurization at 40°C or 50°C prior to setting increased the strength of turkey gels. Similar effects of prior pressurization, but of lesser magnitude, occurred in gels formed by directly or subsequently (following setting) cooking at 90°C. SDS-PAGE confirmed that myosin crosslinking occurred due to TGase activity during the setting treatment, which had survived prior pressure treatment. High pressure rendered protein substrates more accessible to TGase thereby enhancing intermolecular cross-link formation and gel strength.